Q: Should I leave my bubble aeration system running in my farm pond all winter long? – Steve in Minnesota

A: The short answer: Yes, you should keep your aeration system running all winter long. No matter the season, for the health of your fish, you want to breathe that life-giving oxygen into your pond or lake. A bubble aeration system, like the Airmax® Aeration System, keeps the oxygen well-dispersed throughout the water column and prevents the water from stratifying; it also keeps a hole in the ice to allow harmful gasses to escape.

Stir Up the Strata

As the summer cools to winter, a shift happens below your pond’s surface. If the water is not circulated, it naturally separates by temperature: In the summer, the warm oxygen-rich water sits on the top while the cool water, thick with toxic gasses, sits at the bottom. As winter approaches, those different pools of water will flip. The cool water – and all the gasses – rises to the top while the warm water sinks. The pools of water mix – and in extreme cases – this stratification, seasonal shift, and toxic gas distribution can cause a winter fish kill.

A bubbler aeration system prevents that. If the water is churned and moved all year long, it will not stratify. The water at the top and bottom will remain the same temperature, oxygen will be saturated throughout the entire water column, and the gasses will not build up. That makes for an ideal environment for the fish.

Keeps a Hole in the Ice

If your pond freezes over completely and there is no hole in the ice, the decaying matter in your pond (all the fish waste and detritus that naturally break down beneath the surface) releases deadly gasses that are trapped underneath the ice. Prolonged, this will cause a winter fish kill. A bubbler aeration system stops this from happening. The moving and cycling water creates a hole in the ice, allowing the harmful gasses to escape while allowing healthy oxygen in.

A word of caution: If you want to ice skate on your pond and you’re not concerned about fish throughout the winter, we recommend you turn off your aeration system completely. That way, the pond will freeze solid and you’ll be safe while you have some winter fun.

14 Responses

We have our aeration system mainly to deter algal growth and overall gunk in our one-acre, 12 ft deep pond. Because the bubbler is so expensive to run and we have not had winter fish kill problems with no bubbler, we would really like to keep it off in the winter. Will this have an effect on spring/summer algal blooms?

Hi Jane – Anytime you can leave aeration running the better as it will continue to help breakdown the muck that is providing the food source and keeping the pond circulated. This however does also not guaranteed that you would not have blooms in the spring if you did run it. If you choose to turn it off for the winter that is fine just start again early in the spring once ice melts. Since the warmer and cooler water will separate over the winter run your system for only a few hours at a time and increase the time each day to slowing mix the water back together to avoid turning over the pond to quickly.

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I have been reading all the comments on running the airmax system during the winter months – my pond is approxiately 6 feet deep and 15×15 width – my plan is to keep the air max running and also the waterfall filtration system – we live near the Savannah Ga area and do have some teen termps during the winter months – do I need to worry about killing my fish from too cold water temp??

Hi Jan,
I would recommend moving your diffuser plate into the shallower end of your pond, or floating it closer to the surface. This will provide the necessary opening in your ice and add oxygen to your pond during the winter months. Having it elevated out of the deepest part of your pond will keep the deeper water undisturbed and the water warmer for your fish at the deeper depths. When the spring and summer return, place your diffuser plate back into the deepest part of your pond.

I use a net to skim the bottom of my pond every few days or so starting early autumn. Living in Maryland, for the winter I use a pond heater that automatically turns on when the temps. are at 32 degrees which leaves an opening in the ice so the toxic gasses can escape. I’ve been doing this for 12 yrs. & all my fish (no Koi) have made it.

How do I keep aeration going in my 1900 gallon water feature that is 75-100 feet from the house? At below freezing temps here in upstate NY a small air stone pump will Freeze up , won’t it? If I keep the pump in the house, will it be able to pump air that far?

Hi Carol,
An aeration system that is located by the pond side, elevated off the ground and protected from the elements, will operate very well during the winter months. This requires a power source at or near your pond — extension cords are not recommended to be used with aeration systems. For protection from the weather, there are faux rock covers that work effectively and blend into the surrounding scenery.

I highly disagree with leaving the aerator on thru the winter as usual. 2 years ago I left one of my 2 diffusers on throughout the winter…it was in about 17 feet of water. Come spring, I had lost at least 150 fish. For 3 years prior, I didn’t have an aerator, and kept a few holes open thru winter with an auger. I never lost a fish. Numerous people told me afterwards that the aerator froze the fish because it kept the entire pond cold…the fish had no warmer water to get to.
Last year I shut 1 diffuser down completely, and moved the other into 3 feet of water near the edge of the pond. I put it on a timer so that it didn’t run all the time…it just kept the ice open. The animals had a watering hole, and a didn’t lose a single fish.

Don, From reading your post, I suspect that when you had your aeration plate at 17 feet deep, this was near the deepest part of your pond. Usually, you want your diffuser at the average depth of your pond, especially for winter time aeration. Fish will go dormant for the winter in the deepest part of the pond, so having the diffuser plate located in that section would cause some disturbance. At average depth, or just a few feet below the surface for the winter, you will avoid this disturbance. Keeping the hole open in the ice for oxygen and gas exchange is the main goal.

I remember reading, either on your website or elsewhere, that when a pond is too shallow, leaving a bubbler on during the winter may also be bad for the fish because it takes away the warmer lower water layer (even though it does so many good things that your article mentions). My pond is 1/3 acre and is only 5 1/2 feet deep in the middle. Is this too shallow to leave the bubbler on all winter? I’ve had my bubbler since August and that and the Pond Clear have really cleaned up my pond.

I am in a Norther Climate and I thought that I had read that by leaving your aeration system on all winter long I ran the risk of hyper cooling my pond. I remember reading that if I left the aeration system on all winter natural themal layers would not develop and the fish would not find a “comfortable” layer to live in because all of the water would be near freezing. I read this condition could also cause a fish kill. Please sort out the apparent contradiction.